Honestly, I’m surprised it took me this long to pick up on how Rei’s feelings towards Asuka really are.

She doesn’t really express herself much, but apart from some biting remarks, she seemed to be legitimately indifferent towards her, while Asuka was pretty clear in her dislike of Rei, and made it explicitly known to us.

But now it seems like Rei may have hated Asuka much sooner and much more than vice-versa. In this scene from episode 14, also known as the clipshow we don’t talk about, Rei makes it pretty clear that she absolutely despises the colour red. She explicitly associates it with blood and mankind in general in her monologue, but given the prominence in the show, there are at least two noteworthy elements focusing heavily on the colour red.

The first is of course Asuka, who is drenched with red in everything she does. This association is easily interpreted as Rei secretly despising Asuka from the start, even if she never acted on it. In this case, it’s interesting to note that while she was rather rude and putting Rei down, Asuka did attempt to make several genuine attempts to befriend Rei, with the most noteworthy occasion seen in episode 12, where Asuka went out of her way to ensure that Rei could join them in their celebratory dinner. Meanwhile, Rei simply didn’t give a shit about the redhead. She’s ice cold.

The other notable instance of the colour red in association with Rei is seen with Rei herself, specifically in her eye colour. Eyes are traditionally seen as the windows of the soul, and the use of the colour red here is largely symbolic. (A similar instance of such symbolism with regard to eyes is seen with Gendo, whose shades metaphorically close him off from the world)

Rei’s soul, as we later learn, is not truly hers, but in fact comes from Lilith, a monster which isn’t human at all, even if she, in fact created it. Rei detests this, and tries to assert that she is her own self, even if she cannot shake of the feeling of this “wrong” presence within her, serving as one of her primary personal conflicts throughout the show. Essentially, Rei hates this presence inside her, her “soul”.

It’s quite an interesting visual metaphor, and the subtle allusion to Rei’s actual feelings helps a lot to add to her character.